Abstract: Disclosed is a sintered gear composed of a sintered alloy having a metal matrix and pores. The tooth surface (2, 3, 4) of the tooth and the bottom land (5) have a densified layer (11) in which the porosity is reduced to 10% or less from the sintered alloy. The densified layer at the tooth surface is formed with a thickness of 300 to 1,000 microns, and the densified layer at the bottom land is formed with a thickness of 10 to 300 microns. The boundary surface of the densified layer is continuous from the tooth surface side to the bottom land side so as not to have a substantial level difference.

Abstract: A sintered sprocket for a silent chain is obtained from a material with few addition elements by a simple densifying method. The sintered sprocket is made of an ferrous material having an ovarall composition containing Cu at 1 to 2%, C at 0.5 to 0.8%, Mn as an inevitable impurity at 0.10% or less, and balance of Fe and other inevitable impurities by mass and has a density of 7.1 Mg/m3 or higher, 65 HRA or higher as a hardness in the gear teeth, and a martensite, sorbite, bainite, or their mixed structure as a cross-sectional microscopic structure in at least the gear teeth and the peripheral area of the gear teeth.

Abstract: A sintered sprocket for a silent chain is obtained from a material with few addition elements by a simple densifying method. The sintered sprocket is made of an ferrous material having an ovarall composition containing Cu at 1 to 2%, C at 0.5 to 0.8%, Mn as an inevitable impurity at 0.10% or less, and balance of Fe and other inevitable impurities by mass and has a density of 7.1 Mg/m3 or higher, 65 HRA or higher as a hardness in the gear teeth, and a martensite, sorbite, bainite, or their mixed structure as a cross-sectional microscopic structure in at least the gear teeth and the peripheral area of the gear teeth.

Abstract: A sintered sprocket has a high overall density and excellent contact pressure resistance. The sprocket is produced from a sintered alloy selected from the following alloys ((1) to (3)), is densified to have a relative density of 95% or higher in the surface layer of the gear teeth by forming by rolling, having a surface hardness of 700 HV or higher, and is useful for a crankshaft, a cam shaft, a balancer shaft, or a water pump shaft of an internal combustion engine: (1) an Fe—Mo—C based sintered alloy containing Mo at 1.0 to 2.0% by mass; (2) an Fe—Mo—Ni—C based sintered alloy containing Mo at more than 1.0 and not more than 2.0% by mass, and Ni at more than 1.0 and not more than 2.5% by mass, or (3) an Fe—Mo—Ni—Cu—C based sintered alloy containing Mo at 0.3 to 1.0% by mass, Ni at not less than 1.5 to less than 3.0% by mass, and Cu at 1.0 to 2.5% by mass.

Abstract: Disclosed is a sintered gear composed of a sintered alloy having a metal matrix and pores. The tooth surface (2, 3, 4) of the tooth and the bottom land (5) have a densified layer (11) in which the porosity is reduced to 10% or less from the sintered alloy. The densified layer at the tooth surface is formed with a thickness of 300 to 1,000 microns, and the densified layer at the bottom land is formed with a thickness of 10 to 300 microns. The boundary surface of the densified layer is continuous from the tooth surface side to the bottom land side so as not to have a substantial level difference.

Abstract: A sintered sprocket has a high overall density and excellent contact pressure resistance. The sprocket is produced from a sintered alloy selected from the following alloys ((1) to (3)), is densified to have a relative density of 95% or higher in the surface layer of the gear teeth by forming by rolling, having a surface hardness of 700 HV or higher, and is useful for a crankshaft, a cam shaft, a balancer shaft, or a water pump shaft of an internal combustion engine: (1) an Fe—Mo—C based sintered alloy containing Mo at 1.0 to 2.0% by mass; (2) an Fe—Mo—Ni—C based sintered alloy containing Mo at more than 1.0 and not more than 2.0% by mass, and Ni at more than 1.0 and not more than 2.5% by mass, or (3) an Fe—Mo—Ni—Cu—C based sintered alloy containing Mo at 0.3 to 1.0% by mass, Ni at not less than 1.5 to less than 3.0% by mass, and Cu at 1.0 to 2.5% by mass.

Abstract: A sintered sprocket for a silent chain is obtained from a material with few addition elements by a simple densifying method. The sintered sprocket is made of an ferrous material having an ovarall composition containing Cu at 1 to 2%, C at 0.5 to 0.8%, Mn as an inevitable impurity at 0.10% or less, and balance of Fe and other inevitable impurities by mass and has a density of 7.1 Mg/m3 or higher, 65 HRA or higher as a hardness in the gear teeth, and a martensite, sorbite, bainite, or their mixed structure as a cross-sectional microscopic structure in at least the gear teeth and the peripheral area of the gear teeth.